Kinetlcs Study On Chiral Extraction Separation Of Hydroxy-(2-methyl-phenyl)-acetic Acid And Amino Acid Enantiomers

In this paper, chiral extract separation technique was applied to investigate the kinetic mechanism of reactive extraction of o-methyl mandelic acid enantiomers (HA), phenylalanine enantiomers (Phe), phenylglycine enantiomers (PhgH) and D-p-Hydroxyphenylglycine enantiomers (D-HPG). The optimal extraction parameter was acquired through experiments, The model of kinetics of chiral extraction was established in this paper. The following contents are the substance and results in this peper:In system of the reaction extraction separation of HA enantiomer. The kinetics of the extraction process was describe by homogeneous reaction model and the theory of chiral extraction with chemical reaction. Some influencing factors on initial extraction rate including stirring speed, interfacial area, pH value of aqueous phase, the initial concentration of HA enantiomers in organic phase and the concentration of hydrophilic extractant (HP-β-CD) in aqueous phase, were separately discussed. Meantime. It has been found in experiment results that the first and second order reactions respectively belong to the extraction reaction for the concentration of HA and HP-β-CD. The results of the forward rate constants of S-HA and R-HA separately equal to4.343×10-4m6/(mol2·s) and4.873×10-4m6/(mol2·s). Has and HaR are calculated as4.682and4.958, respectively.In system of the reaction extraction separation of Phe, PhgH and D-HPG enantiomers. Interface reaction model was selected, the intrinsic kinetics of the extraction process was researched by a modified Lewise cell. The effects of process parameters including stirring speed, interfacial area, pH value of aqueous phase, initial concentration of enantiomers in aqueous phase and initial extractant (BINAP-metal complex) concentration in organic phase on initial extraction rate were separately discussed. the kinetic model was employed to forecast the experient result, comparing the results of prediction with the experiment values. It has been found in the system of reaction extraction separation of Phe enantiomers that the first and half order reactions belong to the extraction reaction for the concentration of D-Phe and BINAP-metal complex, respectively. The results of calculation show that the forward rate constants of D-Phe and L-Phe are equivalent to7.93×10-5m5/2/(mol1/2.s) and1.29×10-4m5/2/(mol1/2.s), separately. In system of reaction extraction separation of PhgH enantiomers, the1.4and0.3order reactions are connected with the extraction reaction for the concentration of D-Phe and BINAP-metal complex, respectively. The forward rate constants of D-PhgH and L-PhgH are separately equivalent to3.14×10-5m3.4/(mol0.7.s) for and4.03×10-5m3.4/(mol0.7.s). In the system of reaction extraction separation of D-HPG enantiomers, the0.6and0.8order reactions are connected with the extraction reaction for the concentration of D-HPG and BINAP-metal complex, respectively. Here, the forward rate constant of D-PhgH is1.0×10-3.5m2.2/(mol0.4·s). The results are almost identical through comparing the model prediction values with the experiment values.